Most of us old folks go by watts per. sq. ft. -n- not lumens .

Lumens could be from weak ass cfl , led sources that are almost usesless once the light source is less than a foot away from it's target . = reasoning for watts -n- not lumens .

Do a search here and at the other sites for "watts per. sq. ft."
your gonna find 40-50 to be optimal .

Why not a pair of 1000's if it's a lumen booner you have ?
2-1000w hortilux = 290,000 lumens where as 2-600w only = 200,000 lumens . 2-1000 = the lumens of 3-600w.

Crispi :jointsmile: